"I was pitching through a lot of stuff," he told The Athletic's Jake Kaplan.
When asked if surgery is on the table for the offseason, McCullers said, "We'll figure it out moving forward."
The 25-year-old was on the disabled list for most of August and September with the forearm injury and was reduced to a relief role upon his return to the mound.
"My focus was to come back and be ready to go for the team in the postseason and do the best I could to pitch when I was called upon and figure out my medical stuff after we hopefully won a World Series," he said. "That didn't happen, so I'll figure it out now in the next couple weeks."
McCullers made five appearances in the playoffs, surrendering four hits and one earned run across five innings pitched.